diff --git a/browser/actors/DecoderDoctorChild.jsm b/browser/actors/DecoderDoctorChild.jsm
new file mode 100644
index 000000000000..c6816bcfd435
--- /dev/null
+++ b/browser/actors/DecoderDoctorChild.jsm
@@ -0,0 +1,32 @@
+/* -*- mode: js; indent-tabs-mode: nil; js-indent-level: 2 -*- */
+/* vim: set ts=2 sw=2 sts=2 et tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+"use strict";
+
+var EXPORTED_SYMBOLS = ["DecoderDoctorChild"];
+
+class DecoderDoctorChild extends JSWindowActorChild {
+  // Observes 'decoder-doctor-notification'. This actor handles most such notifications, but does not deal with notifications with the 'cannot-play' type, which is handled
+  // @param aSubject the nsPIDOMWindowInner associated with the notification.
+  // @param aTopic should be "decoder-doctor-notification".
+  // @param aData json data that contains analysis information from Decoder Doctor:
+  // - 'type' is the type of issue, it determines which text to show in the
+  //   infobar.
+  // - 'isSolved' is true when the notification actually indicates the
+  //   resolution of that issue, to be reported as telemetry.
+  // - 'decoderDoctorReportId' is the Decoder Doctor issue identifier, to be
+  //   used here as key for the telemetry (counting infobar displays,
+  //   "Learn how" buttons clicks, and resolutions) and for the prefs used
+  //   to store at-issue formats.
+  // - 'formats' contains a comma-separated list of formats (or key systems)
+  //   that suffer the issue. These are kept in a pref, which the backend
+  //   uses to later find when an issue is resolved.
+  // - 'decodeIssue' is a description of the decode error/warning.
+  // - 'resourceURL' is the resource with the issue.
+  observe(aSubject, aTopic, aData) {
+    this.sendAsyncMessage("DecoderDoctor:Notification", aData);
+  }
+}
diff --git a/browser/base/content/browser-media.js b/browser/actors/DecoderDoctorParent.jsm
similarity index 70%
rename from browser/base/content/browser-media.js
rename to browser/actors/DecoderDoctorParent.jsm
index fac8e8d4277e..f692522722e4 100644
--- a/browser/base/content/browser-media.js
+++ b/browser/actors/DecoderDoctorParent.jsm
@@ -1,42 +1,59 @@
-/* -*- indent-tabs-mode: nil; js-indent-level: 2 -*-
- * This Source Code Form is subject to the terms of the Mozilla Public
+/* -*- mode: js; indent-tabs-mode: nil; js-indent-level: 2 -*- */
+/* vim: set ts=2 sw=2 sts=2 et tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
 "use strict";
 
-const TELEMETRY_DDSTAT_SHOWN = 0;
-const TELEMETRY_DDSTAT_SHOWN_FIRST = 1;
-const TELEMETRY_DDSTAT_CLICKED = 2;
-const TELEMETRY_DDSTAT_CLICKED_FIRST = 3;
-const TELEMETRY_DDSTAT_SOLVED = 4;
+var EXPORTED_SYMBOLS = ["DecoderDoctorParent"];
 
-let gDecoderDoctorHandler = {
+const { AppConstants } = ChromeUtils.import(
+  "resource://gre/modules/AppConstants.jsm"
+);
+const { Services } = ChromeUtils.import("resource://gre/modules/Services.jsm");
+const { XPCOMUtils } = ChromeUtils.import(
+  "resource://gre/modules/XPCOMUtils.jsm"
+);
+
+XPCOMUtils.defineLazyGetter(this, "gNavigatorBundle", function() {
+  return Services.strings.createBundle(
+    "chrome://browser/locale/browser.properties"
+  );
+});
+
+class DecoderDoctorParent extends JSWindowActorParent {
   getLabelForNotificationBox(type) {
     if (type == "platform-decoder-not-found") {
       if (AppConstants.platform == "win") {
-        return gNavigatorBundle.getString("decoder.noHWAcceleration.message");
+        return gNavigatorBundle.GetStringFromName(
+          "decoder.noHWAcceleration.message"
+        );
       }
       if (AppConstants.platform == "linux") {
-        return gNavigatorBundle.getString("decoder.noCodecsLinux.message");
+        return gNavigatorBundle.GetStringFromName(
+          "decoder.noCodecsLinux.message"
+        );
       }
     }
     if (type == "cannot-initialize-pulseaudio") {
-      return gNavigatorBundle.getString("decoder.noPulseAudio.message");
+      return gNavigatorBundle.GetStringFromName("decoder.noPulseAudio.message");
     }
     if (type == "unsupported-libavcodec" && AppConstants.platform == "linux") {
-      return gNavigatorBundle.getString(
+      return gNavigatorBundle.GetStringFromName(
         "decoder.unsupportedLibavcodec.message"
       );
     }
     if (type == "decode-error") {
-      return gNavigatorBundle.getString("decoder.decodeError.message");
+      return gNavigatorBundle.GetStringFromName("decoder.decodeError.message");
     }
     if (type == "decode-warning") {
-      return gNavigatorBundle.getString("decoder.decodeWarning.message");
+      return gNavigatorBundle.GetStringFromName(
+        "decoder.decodeWarning.message"
+      );
     }
     return "";
-  },
+  }
 
   getSumoForLearnHowButton(type) {
     if (
@@ -49,7 +66,7 @@ let gDecoderDoctorHandler = {
       return "fix-common-audio-and-video-issues";
     }
     return "";
-  },
+  }
 
   getEndpointForReportIssueButton(type) {
     if (type == "decode-error" || type == "decode-warning") {
@@ -59,20 +76,33 @@ let gDecoderDoctorHandler = {
       );
     }
     return "";
-  },
+  }
 
-  receiveMessage({ target: browser, data: data }) {
-    let box = gBrowser.getNotificationBox(browser);
+  receiveMessage(aMessage) {
+    // The top level browsing context's embedding element should be a xul browser element.
+    let browser = this.browsingContext.top.embedderElement;
+    // The xul browser is owned by a window.
+    let window = browser?.ownerGlobal;
+
+    if (!browser || !window) {
+      // We don't have a browser or window so bail!
+      return;
+    }
+
+    let box = browser.getTabBrowser().getNotificationBox(browser);
     let notificationId = "decoder-doctor-notification";
     if (box.getNotificationWithValue(notificationId)) {
+      // We already have a notification showing, bail.
       return;
     }
 
     let parsedData;
     try {
-      parsedData = JSON.parse(data);
+      parsedData = JSON.parse(aMessage.data);
     } catch (ex) {
-      Cu.reportError("Malformed Decoder Doctor message with data: " + data);
+      Cu.reportError(
+        "Malformed Decoder Doctor message with data: " + aMessage.data
+      );
       return;
     }
     // parsedData (the result of parsing the incoming 'data' json string)
@@ -104,7 +134,7 @@ let gDecoderDoctorHandler = {
     if (!/^\w+$/im.test(decoderDoctorReportId)) {
       return;
     }
-    let title = gDecoderDoctorHandler.getLabelForNotificationBox(type);
+    let title = this.getLabelForNotificationBox(type);
     if (!title) {
       return;
     }
@@ -146,11 +176,13 @@ let gDecoderDoctorHandler = {
       }
 
       let buttons = [];
-      let sumo = gDecoderDoctorHandler.getSumoForLearnHowButton(type);
+      let sumo = this.getSumoForLearnHowButton(type);
       if (sumo) {
         buttons.push({
-          label: gNavigatorBundle.getString("decoder.noCodecs.button"),
-          accessKey: gNavigatorBundle.getString("decoder.noCodecs.accesskey"),
+          label: gNavigatorBundle.GetStringFromName("decoder.noCodecs.button"),
+          accessKey: gNavigatorBundle.GetStringFromName(
+            "decoder.noCodecs.accesskey"
+          ),
           callback() {
             let clickedInPref = Services.prefs.getBoolPref(
               buttonClickedPref,
@@ -163,17 +195,17 @@ let gDecoderDoctorHandler = {
             let baseURL = Services.urlFormatter.formatURLPref(
               "app.support.baseURL"
             );
-            openTrustedLinkIn(baseURL + sumo, "tab");
+            window.openTrustedLinkIn(baseURL + sumo, "tab");
           },
         });
       }
-      let endpoint = gDecoderDoctorHandler.getEndpointForReportIssueButton(
-        type
-      );
+      let endpoint = this.getEndpointForReportIssueButton(type);
       if (endpoint) {
         buttons.push({
-          label: gNavigatorBundle.getString("decoder.decodeError.button"),
-          accessKey: gNavigatorBundle.getString(
+          label: gNavigatorBundle.GetStringFromName(
+            "decoder.decodeError.button"
+          ),
+          accessKey: gNavigatorBundle.GetStringFromName(
             "decoder.decodeError.accesskey"
           ),
           callback() {
@@ -197,7 +229,7 @@ let gDecoderDoctorHandler = {
             }
 
             params.append("details", JSON.stringify(details));
-            openTrustedLinkIn(endpoint + "?" + params.toString(), "tab");
+            window.openTrustedLinkIn(endpoint + "?" + params.toString(), "tab");
           },
         });
       }
@@ -215,14 +247,5 @@ let gDecoderDoctorHandler = {
       Services.prefs.clearUserPref(formatsPref);
       Services.prefs.clearUserPref(buttonClickedPref);
     }
-  },
-};
-
-window
-  .getGroupMessageManager("browsers")
-  .addMessageListener("DecoderDoctor:Notification", gDecoderDoctorHandler);
-window.addEventListener("unload", function() {
-  window
-    .getGroupMessageManager("browsers")
-    .removeMessageListener("DecoderDoctor:Notification", gDecoderDoctorHandler);
-});
+  }
+}
diff --git a/browser/actors/moz.build b/browser/actors/moz.build
index d957a93760df..749ce211d8c0 100644
--- a/browser/actors/moz.build
+++ b/browser/actors/moz.build
@@ -55,6 +55,8 @@ FINAL_TARGET_FILES.actors += [
     'ContentSearchParent.jsm',
     'ContextMenuChild.jsm',
     'ContextMenuParent.jsm',
+    'DecoderDoctorChild.jsm',
+    'DecoderDoctorParent.jsm',
     'DOMFullscreenChild.jsm',
     'DOMFullscreenParent.jsm',
     'EncryptedMediaChild.jsm',
diff --git a/browser/base/content/browser.xhtml b/browser/base/content/browser.xhtml
index 965fb8b98b81..c208146cffc8 100644
--- a/browser/base/content/browser.xhtml
+++ b/browser/base/content/browser.xhtml
@@ -96,7 +96,6 @@
   if (!AppConstants.MOZILLA_OFFICIAL) {
     Services.scriptloader.loadSubScript("chrome://browser/content/browser-development-helpers.js", this);
   }
-  Services.scriptloader.loadSubScript("chrome://browser/content/browser-media.js", this);
   Services.scriptloader.loadSubScript("chrome://browser/content/browser-pageActions.js", this);
   Services.scriptloader.loadSubScript("chrome://browser/content/browser-sidebar.js", this);
   Services.scriptloader.loadSubScript("chrome://browser/content/browser-tabsintitlebar.js", this);
diff --git a/browser/base/content/moz.build b/browser/base/content/moz.build
index 5ef1ed0909aa..8efe140ef0f7 100644
--- a/browser/base/content/moz.build
+++ b/browser/base/content/moz.build
@@ -139,9 +139,6 @@ with Files("browser-fullZoom.js"):
 with Files("browser-gestureSupport.js"):
     BUG_COMPONENT = ("Core", "Widget: Cocoa")
 
-with Files("browser-media.js"):
-    BUG_COMPONENT = ("Core", "Audio/Video: Playback")
-
 with Files("browser-pageActions.js"):
     BUG_COMPONENT = ("Firefox", "Toolbars and Customization")
 
diff --git a/browser/base/content/test/performance/browser_startup_content.js b/browser/base/content/test/performance/browser_startup_content.js
index 2dcceb876eee..df00da7e0dc2 100644
--- a/browser/base/content/test/performance/browser_startup_content.js
+++ b/browser/base/content/test/performance/browser_startup_content.js
@@ -67,7 +67,6 @@ const known_scripts = {
   ]),
   processScripts: new Set([
     "chrome://global/content/process-content.js",
-    "resource:///modules/ContentObservers.js",
     "resource://gre/modules/extensionProcessScriptLoader.js",
   ]),
 };
diff --git a/browser/base/content/test/performance/browser_startup_content_subframe.js b/browser/base/content/test/performance/browser_startup_content_subframe.js
index 6c27112f7ab4..f95a7075c8bd 100644
--- a/browser/base/content/test/performance/browser_startup_content_subframe.js
+++ b/browser/base/content/test/performance/browser_startup_content_subframe.js
@@ -60,7 +60,6 @@ const known_scripts = {
   ]),
   processScripts: new Set([
     "chrome://global/content/process-content.js",
-    "resource:///modules/ContentObservers.js",
     "resource://gre/modules/extensionProcessScriptLoader.js",
   ]),
 };
diff --git a/browser/base/jar.mn b/browser/base/jar.mn
index 5cf7af4f635d..fd5b25719019 100644
--- a/browser/base/jar.mn
+++ b/browser/base/jar.mn
@@ -48,7 +48,6 @@ browser.jar:
         content/browser/browser-fullScreenAndPointerLock.js (content/browser-fullScreenAndPointerLock.js)
         content/browser/browser-fullZoom.js           (content/browser-fullZoom.js)
         content/browser/browser-gestureSupport.js     (content/browser-gestureSupport.js)
-        content/browser/browser-media.js              (content/browser-media.js)
         content/browser/browser-pageActions.js        (content/browser-pageActions.js)
         content/browser/browser-places.js             (content/browser-places.js)
         content/browser/browser-safebrowsing.js       (content/browser-safebrowsing.js)
diff --git a/browser/components/BrowserGlue.jsm b/browser/components/BrowserGlue.jsm
index 9cc62d03f637..da5fdd7d0b2c 100644
--- a/browser/components/BrowserGlue.jsm
+++ b/browser/components/BrowserGlue.jsm
@@ -377,6 +377,20 @@ let JSWINDOWACTORS = {
     allFrames: true,
   },
 
+  DecoderDoctor: {
+    parent: {
+      moduleURI: "resource:///actors/DecoderDoctorParent.jsm",
+    },
+
+    child: {
+      moduleURI: "resource:///actors/DecoderDoctorChild.jsm",
+      observers: ["decoder-doctor-notification"],
+    },
+
+    messageManagerGroups: ["browsers"],
+    allFrames: true,
+  },
+
   DOMFullscreen: {
     parent: {
       moduleURI: "resource:///actors/DOMFullscreenParent.jsm",
diff --git a/browser/modules/ContentObservers.js b/browser/modules/ContentObservers.js
deleted file mode 100644
index ae2718b5aca8..000000000000
--- a/browser/modules/ContentObservers.js
+++ /dev/null
@@ -1,31 +0,0 @@
-/* -*- indent-tabs-mode: nil; js-indent-level: 2 -*- */
-/* This Source Code Form is subject to the terms of the Mozilla Public
- * License, v. 2.0. If a copy of the MPL was not distributed with this
- * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
-
-/**
- * This process script is for small observers that we want to register
- * once per content process, usually in order to forward content-based
- * observer service notifications to the chrome process through
- * message passing. Using a process script avoids having them in
- * content.js and thereby registering N observers for N open tabs,
- * which is bad for perf.
- */
-
-"use strict";
-
-const { Services } = ChromeUtils.import("resource://gre/modules/Services.jsm");
-
-var gDecoderDoctorObserver = function(subject, topic, data) {
-  let win = subject.top;
-  let mm = getMessageManagerForWindow(win);
-  if (mm) {
-    mm.sendAsyncMessage("DecoderDoctor:Notification", data);
-  }
-};
-
-function getMessageManagerForWindow(aContentWindow) {
-  return aContentWindow.docShell.messageManager;
-}
-
-Services.obs.addObserver(gDecoderDoctorObserver, "decoder-doctor-notification");
diff --git a/browser/modules/moz.build b/browser/modules/moz.build
index 6a8b14b684a7..e60199812cec 100644
--- a/browser/modules/moz.build
+++ b/browser/modules/moz.build
@@ -131,7 +131,6 @@ EXTRA_JS_MODULES += [
     'BrowserUsageTelemetry.jsm',
     'BrowserWindowTracker.jsm',
     'ContentCrashHandlers.jsm',
-    'ContentObservers.js',
     'Discovery.jsm',
     'EveryWindow.jsm',
     'ExtensionsUI.jsm',
diff --git a/dom/media/doctor/DecoderDoctorDiagnostics.cpp b/dom/media/doctor/DecoderDoctorDiagnostics.cpp
index 6fccc73ffd40..d2f20402088f 100644
--- a/dom/media/doctor/DecoderDoctorDiagnostics.cpp
+++ b/dom/media/doctor/DecoderDoctorDiagnostics.cpp
@@ -236,7 +236,8 @@ enum class ReportParam : uint8_t {
 };
 
 struct NotificationAndReportStringId {
-  // Notification type, handled by browser-media.js.
+  // Notification type, handled by DecoderDoctorChild.jsm and
+  // DecoderDoctorParent.jsm.
   dom::DecoderDoctorNotificationType mNotificationType;
   // Console message id. Key in dom/locales/.../chrome/dom/dom.properties.
   const char* mReportStringId;
diff --git a/toolkit/components/processsingleton/MainProcessSingleton.jsm b/toolkit/components/processsingleton/MainProcessSingleton.jsm
index 6acbc10c9995..d1f1022cf866 100644
--- a/toolkit/components/processsingleton/MainProcessSingleton.jsm
+++ b/toolkit/components/processsingleton/MainProcessSingleton.jsm
@@ -35,10 +35,6 @@ MainProcessSingleton.prototype = {
           "chrome://global/content/process-content.js",
           true
         );
-        Services.ppmm.loadProcessScript(
-          "resource:///modules/ContentObservers.js",
-          true
-        );
         break;
       }
 
diff --git a/tools/lint/eslint/modules.json b/tools/lint/eslint/modules.json
index 8020c32bf4b4..849783fc4dce 100644
--- a/tools/lint/eslint/modules.json
+++ b/tools/lint/eslint/modules.json
@@ -38,7 +38,6 @@
   "content-process.jsm": ["init"],
   "content.jsm": ["registerContentFrame"],
   "ContentCrashHandlers.jsm": ["TabCrashHandler", "SubframeCrashHandler", "UnsubmittedCrashHandler"],
-  "ContentObservers.js": [],
   "ContentPrefUtils.jsm": ["ContentPref", "cbHandleResult", "cbHandleError", "cbHandleCompletion", "safeCallback", "_methodsCallableFromChild"],
   "cookies.js": ["Cookies"],
   "CoverageUtils.jsm": ["CoverageCollector"],